In the calibration of weighing scales, tensometers, and similar instruments particularly those used for heavy objects, various standard weights of precisely known weight values are used. These standard weights may range anywhere from 100 pounds to 5,000 pounds and greater and normally require heavy duty hoists to lift and move the weights into proper positions for calibrating purposes. For purposes of lifting the weights, they may be provided with conventional eyes which are secured in the top surface of the weight and to which a hoist hook may readily be coupled. On the other hand, the presence of these eyes protruding from each of the standard weights prevents stacking of the weights in a convenient manner, the weights themselves generally being in the shape of rectangular blocks.
To overcome the foregoing stacking problem, various types of socket openings have been provided in the top surface of the weights for cooperation with eyes provided with bayonette couplings for example so that the eyes can be removed from the weights. On the other hand, such disconnectable type eyes as have been available and the geometry of cooperating openings in the weights themselves for receiving the eyes have oftentimes been difficult to manually connect and disconnect. In this respect, any such construction must be capable of withstanding extremely high tension forces particularly when very heavy weights are involved. Accidental uncoupling of the eye from the weight when it is hoisted upwardly and being moved can result in extensive damage and possible serious physical injury to personnel in the area.
In other instances, there are situations where it is necessary to lift heavy weights from a particular environment; for example, in lifting engines from an automobile chassis or in attempting to move other similar type heavy loads wherein projecting eyes for coupling to a hoist could interfere with other components in the environment in which the object is used. In such applications, it would also be desirable to provide a removable eye which can be easily manually connected and disconnected and exhibit the necessary strength and reliability essential for safe movement of the object.